If you're not a brunette, I'd pass on the coffee. If you're a blonde, it can darken your hair and if you're a red, it will darken you too. Mayo is just whipped egg white and oil. So whisk up an egg white, mix in some extra oil, honey, and for god sakes, use the baby food bannana or you will be picking banana chunks out of your hair. Try different oils and fruits until you find the combo your hair likes.